High intensity luminous tube



May 26, 1942. R. u. CLARK HIGH INTENSITY LUMINOUS TUBE Filed Dec. 9, 1940 PATENT oFFlcE it: GH. INTENSITY LUMINOUS TUBE alu s v. Clark, rm Wayne, mu.

Application December 9, 1940. Serial No. 369,145

lCiaims. (cine-122i Fig. 2 is a. horizontal section taken on the line 2-2 of Fig. 1; and

This inventionrelates to intensity luminous tubes of the gaseous glow -discharge type in which extremely brilliant flashes of light may be produced by the sudden discharge through the I tube of large amounts of electrical energy. In

general, the chief object of this type of tube is for other purposes where the object must be brightly illuminated in order to bring out suitable contrast between various portions of the subject as, for instance, in the case of still photography of living subjects.

Heretoforain tubes designed for the above purpose, the chief diiliculty has been in originating a tube that will glv'ean extremely high intensity of light and at the same time a relatively long useful life. It has also been found very dimcult to produce a tube of the gas discharge type that will maintain its starting and operating voltages reasonably close throughout the life of the tube, in view of the fact that any slight impurity in the gas filling or the presence of occluded gases in the tube structure tend to migrate within the tube and cause fairly wide variations in the operating and are breakdown voltages. o i

One object of the present invention is to provide a tube which will avoid the above recited disadvantages.

Furthermore, in prior tubes which the invention relates, it has been necessary to includea third internal element or control device in order to assist the tube in breaking down electrically through the gas at suitable uniform voltages for commercial use as in certain typesof work the breakdown voltage mustbe fairly constant to .give an even timing of the light operation.

'A further-object of the" invention is to provide through a tube constructed according to the present invention;

of the type to Fig. 3- is a similar view of Fig. 1 showing a modification. 1

In the drawing, the reference numeral i indicates the envelope of the tube which may be of glass or any other suitable material; 2 isthe reentrant portion thereof; 3 and 4 the lead wires which are sealed within the re-entrant portion 2 and at their inner ends are respectively connected to the anode 5 and the cathode 6.

The anode 5 is, in accordance with the invention, made of porous metal composed of suitable gettering metal particles. To form the anode the particles are pressed into the desired shape under high pressure and sintered in a vacuum so as to be relatively gas free and in order to make them adhere firmly to each other.

In using gettering metals for the formation of the anode, I have found columbium metal powders in the above form to be ususually effective in that their employment results in maintaining the tube in condition to give a relatively constant breakdown voltage. -The importance of utilizing an anode of this type will accordingly at'once be appreciated by those skilled in the art.

In operation it has been found that the par-' tieular type of anode electrode above described keeps the gas within the-device or tubepure and that said device or tube thenfunctions in a relatively uniform manner throughout an unusually long period of time.

The cathode element 6 may take any suitable form and for many types of service may consist merely of an ordinary metallic wire of sufficient bulk to prevent excessive sputtering under the conditions of operation for which it is to be employed. For special purposes, the cathode may be activated or coated with various alkali metals or otherwise made highlylactive. Although a cold cathode structure is preferred, it is obvious that a heated cathode may be substituted.

The cathode 6 is enclosed in a housing member which may conveniently take the form of a constricted tube of suitable transparent material such as glass, silica or the like, and which preferably extendsfrom the upper surface of the re-entrant portion 2 to a short distancebelow the upper wall of. the envelope as shown in the drawing. The cathode tube 1 is open atits upper end and acts to conductor guide'an extremely intense discharge into the envelopethrough its said open end.

The cathode tube 1 ispreferably suitably crooked .or bent, as shown at 8, to prevent the spread of sputtering from the cathode through the entire lengthoi' said tube I.

- To further eliminate the possibility of sputtering spread a desirable form of strainer or baille 9 may be positioned within the cathode tube I as shown in Fig. 3. This strainer or bafiie may be of metal or other suitable material and is preferably so fabricated as to allow the discharge to pass whilst preventing the flow of small metal particles.

To further improve the eiiectiveness of the high intensity or high powered disruptive discharges are used as the metal tends to come of! in granular form rather than in the form of very finely divided parts, particularly where a porous columbium cathode is used.

The accompanying drawing illustrates the preferred form of the invention, though it is to be understood that the invention is not'limited to the exact details of construction shown and described, as it is obvious that various modifications thereof, within the scope of the claims, will occur baiile it may be fabricated of magnetic materials of the more modern types which may be highly possibilities at a given cost.

The envelope is normally filled to a" relatively high pressure. In many of the devices already tested, perssures of the order of ten to thirty millimeters have been employed but it is understood that there is no reason why the device should be limited to any close range of pressures as'it will operate throughout avery wide range,

provided suitable input voltages are used. I may.

also employ an ionizable vapor. v

The electrodes are normally supplied with voltage from a condenser or similar storage device and the ignition is excited by means of an ex-' I temal surge of current of high intensity, the same being applied externally to the glass and to one of the inner electrodes of the tube through. suitable connections.

Under operating conditions the device or tube may be run at intermittent frequencies covering relatively long periods or may be operated .upto

' columbium sintered metal powders to prevent the to persons skilled in the art.

I claim:

1. A highintensity luminous tube consisting in a gas filled envelope and an anode and cathode sealed within said envelope, said anode being entirely of porous metal composed of nonalkali gettering sintered metal particles.

2. A high intensity luminous tube consisting in a gas filled envelope and an anode and cathode sealed within said envelope, said anode being entirely-composed of a self-supporting mass of fouling of said tube.

3. A high intensity luminous tube comprising a gas-filled envelope, a porous columbium anode, a cathode sealed within said envelope and aninner tube opening into said envelope surrounding frequencies of many hundred per second or more 7 when desired and suitably designedr 7 For operationthrough quite a wide range of frequencies the device can be run as a diode oscillator without the need of any external trigfrequency of operation, I have found the crook or bend in the inner'tube I at pointlisvery desirable to help prevent the smf flfi ofjsputtering and I have also found that-by mahm this bend relatively sharp so that the upper ehd'otthe tube is rather wellshielded from theend o'i' the-cathodejthatthe spread ofsputtering is very well controlled. One reason for desiring control the spread of sputtering is to prevent the tendency to lower the breakdown voltage of thetube which is incident to suchspread. in addition to the desire to keep the inner :tllbe relatlvely clean for optical reasons."

In this typeof tube I have also successfully employed cathodes of columbiumme'taljwhich-I find do not cause a very opaque under-com ditions where the columbium cathode to sputter. This is particularlytrue" where every gering device. Under conditions of relativelyhig'h said cathode, said inner tubehaving a sharp bend therein near said cathode. j g

I 4. A high intensity luminous tube comprising a gasfilled envelope; an anode and a cathode sealed within said envelope, a partial enclosure insulating tube surrounding said cathode, and a tapered helicalwire bafiie in said cathode enclosure tube for preventing the spread of sputtering from the cathode within said tube.

5. A high intensity luminous tube comprising a gas filled envelope; an anode and a cathode of magneticmaterial sealed within said envelope, 9.

partial enclosure insulating tube surrounding said cathode, and a magnetized strainer in said cathode enclosure tube for preventing the spread of sputtering from the cathode by traction for said sputter.

, 6. A high intensity luminous tubecomprising a transparent gas filled envelope. are-entrant stem, leads through said stem, a columbium'ca-thode attached to one lead, a constricted crooked transparent tube. surrounding said cathode and extending at least beyond the end of said cathode,

and a porous sintered columbium anode adjacent 1 the'end of said crooked tube. most remote from said cathode, said crooked tube being open at the anodeend. a

7. A vapor electric luminous tube, said tube encompassing a col'umbium-ca'thode and porous columbium anode, are-entrant stem in said tube for supporting said electrodes, an extension of part of said 'stemaroundsaidcathode within said tube to-a point beyond the end of said'cathode "with clearance all around said cathode and a crook in said extension to prevent the spreadof opaquing "sputter from saidcathode combined with an'open end in said extension terminating adiacentsaid anode said anode constantly gettering said tubexand said cathode material sputtering easily .baiiled particles.

' U. CLARK.

its magnetic atv 

